php 在调用 call_user_func() 之前检查类中是否存在函数
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Check if a function exists in a class before calling call_user_func()
提问by S.Visser
In the following code I call a class with call_user_func().
在下面的代码中，我用call_user_func().
if(file_exists('controller/' . $this->controller . '.controller.php')) {
require('controller/' . $this->controller . '.controller.php');
call_user_func(array($this->controller, $this->view));
} else {
echo 'error: controller not exists <br/>'. 'controller/' . $this->controller . '.controller.php';
}
Let's say that the controller has the following code.
假设控制器具有以下代码。
class test {
static function test_function() {
echo 'test';
}
}
When I call call_user_func('test', 'test_function')there isn't any problem. But when I call a function that does not exist, it does not work. Now I want to check first if the function in the class testdoes exist, before I call the function call_user_func.
当我打电话call_user_func('test', 'test_function')时没有任何问题。但是当我调用一个不存在的函数时，它不起作用。现在我想先检查类test中的函数是否存在，然后再调用函数call_user_func。
Is there a function that checks if a function exists in an class or is there another way I can check this?
是否有一个函数可以检查类中是否存在某个函数，或者还有其他方法可以检查这个函数吗？
回答by Elias Van Ootegem
You're looking for method_existsfor starters. But what you shouldcheck, too is whether or not the method is callable. This is done by the helpfully named is_callablefunction:
您正在寻找method_exists初学者。但是您还应该检查该方法是否是callable。这是由有用的命名is_callable函数完成的：
if (method_exists($this->controller, $this->view)
&& is_callable(array($this->controller, $this->view)))
{
call_user_func(
array($this->controller, $this->view)
);
}
But that's just the start of things. Your snippet contains explicit requirecalls, which suggests you're not using an autoloader.
What's more: all you're doing is check file_exists, not if the class was already loaded. Your code, then, will generate a fatal error if, per chance your snippet gets executed twice with the same values for $this->controller.
Begin fixing this by, in the very least, changing your requireto require_once...
但这只是事情的开始。您的代码段包含显式require调用，这表明您没有使用autoloader。
更重要的是：您所做的只是 check file_exists，而不是类是否已经加载。那么，如果您的代码片段每次使用相同的$this->controller.
开始解决这个问题，至少，改变你require的require_once......
回答by ProGM
You can use the PHP function method_exists():
您可以使用 PHP 函数method_exists()：
if (method_exists('ClassName', 'method_name'))
call_user_func(etc...);
or also:
或者：
if (method_exists($class_instance, 'method_name'))
call_user_func(etc...);
回答by GiuServ
From PHP 5.3, you can also use:
从 PHP 5.3 开始，您还可以使用：
if(method_exists($this, $model))
return forward_static_call([$this, $model], $extra, $parameter);
回答by Steyx
Use method_exists($this->controller, $this->view). For your example:
使用method_exists($this->controller, $this->view). 对于您的示例：
if(file_exists('controller/' . $this->controller . '.controller.php') &&
method_exists($this->controller,$this->view)) {
require('controller/' . $this->controller . '.controller.php');
call_user_func(array($this->controller, $this->view));
} else {
echo 'error: controller or function not exists <br/>'. 'controller/' . $this->controller . '.controller.php';
}
